Performance of a Medipix3RX Spectroscopic Pixel Detector With a High Resistivity Gallium Arsenide Sensor

Abstract

High resistivity gallium arsenide is considered a suitable sensor material for spectroscopic X-ray imaging detectors. These sensors typically have thicknesses between a few hundred μm and 1 mm to ensure a high photon detection efficiency. However, for small pixel sizes down to several tens of μm, an effect called charge sharing reduces a detector's spectroscopic performance. The recently developed Medipix3RX readout chip overcomes this limitation by implementing a charge summing circuit, which allows the reconstruction of the full energy information of a photon interaction in a single pixel. In this work, we present the characterization of the first Medipix3RX detector assembly with a 500 μm thick high resistivity, chromium compensated gallium arsenide sensor. We analyze its properties and demonstrate the functionality of the charge summing mode by means of energy response functions recorded at a synchrotron. Furthermore, the imaging properties of the detector, in terms of its modulation transfer functions and signal-to-noise ratios, are investigated. After more than one decade of attempts to establish gallium arsenide as a sensor material for photon counting detectors, our results represent a breakthrough in obtaining detector-grade material. The sensor we introduce is therefore suitable for high resolution X-ray imaging applications.

X-ray deconvolution microscopy

“…Hence, the nearly box-like PSF of the MEDIPIX3RX operated in CSM is one key feature for the XDM method since access to higher spatial frequencies becomes much more efficient. Other studies investigating the imaging characteristics of the MEDIPIX3RX with a GaAs x-ray sensor have reported a MTF that appears to be related to a less box-like PSF [22]. This result however can be explained partly by the fact that GaAs sensors produce x-ray fluorescence which also degrades the spatial resolution and cannot be fully compensated by the CSM.…”

Asic developments for radiation imaging applications: The medipix and timepix family

“…In a similar way to the Si sensor studies, the Timepix chip has acted as the host to many different candidate sensor materials providing invaluable insight into the distribution of defects and the charge collection mechanisms [65][66][67]. The Medipix3RX chip has also been used for the study of GaAs material [68] and for time dependent variations in CdTe material [69].…”

Research into effect of electrochemical etching conditions on the morphology of porous gallium arsenide

“…Gallium arsenide has significant technological importance because it is used for manufacturing sensors [46], solar panels [47], photodetectors [48], etc. In turn, the porous gallium arsenide (por-GaAs) is also widely applied.…”